Best-selling ActiveIce technology works more efficiently and effectively than ever before. Our proprietary self-cooling technology now reacts to increases in your body temperature by dynamically cooling you faster when you need it most. A special additive drives this cooling process via phase changes. which keeps the wicking. breathable. and quick drying ActiveIce technology the ideal solution for anyone who spends serious time in hot. sweaty. sun-baked conditions. This sun hoodie was built for total coverage and comfort. featuring a chafe-free design and dynamic reach to let you stretch. move. and take on the heat.